On October 3rd, 2019 a petition was submitted by The Physicians Committee for Responsible Medicine to the FDA to have all dairy cheese products labeled with the phrase ‘such products contain reproductive hormones that can increase the risk of breast cancer mortality’. Former talk show host and current advocate Jon Stewart has signaled that he supports this proposition. This proposal is based on numerous studies that have linked high-fat dairy diets to increased cancer and mortality rates. Some of the same studies have shown that low-fat dairy products decrease cancer rates. While there is some correlation in the date that says high-fat dairy diets can increase the chance of cancer and mortality there is a lot of work that needs to be done to prove a definitive link between cheese consumption and increased rates of breast cancer and breast cancer mortality. Labeling foods has a direct impact on shopping patterns, and mislabeling food will affect both the producer and the consumer negatively.

Previous studies that have looked at dairy intake and breast cancer rates hypothesized that calcium, vitamin D, insulin-like growth factors, conjugated linoleic acid, and estrogen hormones contained in the dairy products were implicated in cancer development. Specifically, estrogen hormones were looked at because of the high incidence and mortality of estrogen-sensitive breast cancers. Estrogen is a steroid hormone that is lipophilic and can accumulate in fats. Brinkman et al. found that postmenopausal women in the highest quartile as compared to women in the lowest quartile for dairy consumption had a 14% increase in the amount of circulating estradiol¹. Increases in estrogen and estrogen-like hormones have been hypothesized to increase breast cancer rates and a positive correlation has been shown between hormone replacement therapy and breast cancer rates². 

The Roswell Park Cancer Institute looked at various dairy products and their correlation with breast cancer rates. The study looked at milk, yogurt, low-fat cheese, other cheeses, and sweet dairy which included ice cream, pudding, and frozen yogurt. The study found that increases in the consumption of milk, yogurt, low-fat cheese, and sweet dairy led to an inverse association of cancer. On the other hand, high-fat cheeses such as American, cheddar, and cream cheese showed a marginally significant increased risk of breast cancer ³. Kroenke et al. looked at low-fat and high-fat dairy intake compared to the recurrence of breast cancer and mortality. Low-fat dairy diets were not associated with increased cancer rates, however high-fat dairy diets were correlated with an increase of breast cancer mortality and all-cause mortality⁴.

Based on the available data it seems imprudent to label cheese as a confirmed carcinogen. There is not enough evidence to prove that cheese consumption is the causation of breast cancer and breast cancer-related mortality. Labeling a product as a carcinogen can lead to many unintended consequences ranging from a significant disruption of the dairy industry to loss of confidence in the physicians and nutritionists who endorsed the cheese be labeled. Physicians should stay up to date with the current nutritional guidelines and stay current with research coming out. Based on the currently available research physicians should stress a reduction in cheese and other fatty food consumption for all their patients specifically postmenopausal women with increased risk of developing breast cancer. Additionally, consuming fewer fatty food can facilitate weight loss which in turn will result in decreased mortality. Short of labeling cheese as a carcinogen, physicians should lobby their patients to make small lifestyle changes that can result in better outcomes and fewer morbidities.

References 

1. Brinkman MT, Baglietto L, Krishnan K, English DR, Severi G, Morris HA, Hopper JL, Giles GG. Consumption of animal products, their nutrient components and postmenopausal circulating steroid hormone concentrations. European journal of clinical nutrition. 2010;64(2):176.
2. Colditz GA. Relationship between estrogen levels, use of hormone replacement therapy, and breast cancer. Journal of the National Cancer Institute. 1998;90(11):814-23..
3. McCann SE, Hays J, Baumgart CW, Weiss EH, Yao S, Ambrosone CB. Usual consumption of specific dairy foods is associated with breast cancer in the Roswell Park Cancer Institute Data Bank and Biorepository. Current developments in nutrition. 2017;1(3):e000422..
4. Kroenke CH, Kwan ML, Sweeney C, Castillo A, Caan BJ. High-and low-fat dairy intake, recurrence, and mortality after breast cancer diagnosis. Journal of the National Cancer Institute. 2013;105(9):616-23.